25.4mm standard handlebar Vs 31.8mm

We have practically bench tested that standard 25.4mm handlebars/stem combos are sensibly stiffer than 31.8mm oversized combos.

This is due to the disadvantages that are inherent to the wall thickness and the overall dimensioning of 31.8mm handlebars. The phenomena wasn't immediately intuitive and it has been experienced by coincidence, then carefully measured and further investigated.

Here follows a brief explanation.

For the same given conditions (this means same bar width, same stem design, same weight, etc) the oversized 31.8mm handlebars generates bigger forces due to axial resultants of radial clamping. These forces are sensibly lower with the 25.4mm standard.

25.4mm Clamp	31.8mm Clamp
FA is 25% greater on the 31.8mm clamp.

The 31.8mm stem/bar combo developes higher axial force. This, expecially in case of thin/lightweight handlebars, generates small movements at the clamp under load, then a higher flex can be measured at the bar ends.

Geometrically the tube walls of an Overzize handlebars (for the same-weight) are thinner than the walls of standard handlebar.

Oppositely the central section of an oversized bar requires thicker walls in order to react to the higher clamping forces. This wall thickness gives the 31.8 inherent dimensioning limit, that's the main reason why 31.8mm handlebars are heavier.

To acheive the same stiffness of 25.4mm combo you need a sensibly heavier 31.8m combo.

Additional notes

Carbon composites perfom exceptionally well under tension.

Under impact and compression high strenght Alloy definitely offers better performance than Carbon composite.

Carbon/Alloy composite handlebars offer one of the best solution to safely resist under clamp compression and impact forces allowing a high level of rigidity.

 

 

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